What are the production processes of acrylic signs?
Acrylic plates can be divided into casting type and extrusion type according to the production process. The performance of the cast type plate is better than the extrusion type, and the price is also more expensive. The cast type plate is mainly used for engraving, decoration, handicraft production, extrusion type Usually used for advertising signs, light boxes and other production.
Cast molding is used to form plexiglass sheet, bar, and other profiles, that is, using bulk polymerization method to shape profiles. Post-treatment of the molded product is required. Post-treatment conditions are 2h at 60°C and 2h at 120°C.
2. Injection molding
Injection molding uses pellets obtained by suspension polymerization and is molded on an ordinary plunger or screw type injection molding machine. Table 1 shows typical process conditions for polymethyl methacrylate injection molding.
Barrel °C temperature
Rear 180-200 180-200
Front 180-210 210-240
Nozzle temperature °C 180-210 210-240
Mold temperature °C 40-80 40-80
Injection pressure MPa 80-120 80-130
Holding pressure MPa 40-60 40-60
Screw speed rp.m-1 20-30
Injection molding products also need post-treatment to eliminate internal stress, and the treatment is performed in a 70-80°C hot air circulation drying oven. The processing time depends on the thickness of the product, and generally takes about 4 hours.
3. Extrusion molding
Polymethyl methacrylate can also be used for extrusion molding, the use of suspension polymerization of the production of granular materials to prepare plexiglass plate, bar, tube, sheet, etc., but the profiles so prepared, especially the plate, due to the small polymer molecular weight, The mechanical properties, heat resistance, and solvent resistance are all inferior to those of cast-formed parts. The advantages are high production efficiency, especially for pipes and other casting methods. Difficult to manufacture profiles. Extrusion molding can use single-stage or double-stage exhaust extruders, and the length-to-diameter ratio of the screw is generally 20-25.